CN113195962B

CN113195962B - Hydrogen pressure accumulator

Info

Publication number: CN113195962B
Application number: CN201980064918.3A
Authority: CN
Inventors: 和田洋流; 细矢隆史; 荒岛裕信
Original assignee: Japan Steel Works M&E Inc
Current assignee: Japan Steel Works M&E Inc
Priority date: 2018-10-02
Filing date: 2019-09-12
Publication date: 2022-12-23
Anticipated expiration: 2039-09-12
Also published as: JP2020056457A; CN113195962A; EP3862619A4; EP3862619A1; WO2020071088A1; KR20210091702A; US20210348724A1; JP7100553B2

Abstract

Provided is a hydrogen accumulator capable of suppressing hydrogen-induced cracking of a cylinder. In a hydrogen accumulator according to one embodiment, a gap portion (G) that separates an inner peripheral surface of a cylinder block (10) from an outer peripheral surface of a cylinder head (20) is provided between a female screw portion (10 a) of the cylinder block (10) into which the cylinder head (20) is screwed and a resin seal (30). A first through hole (41) for discharging the gas in the gap portion (G) to a discharge pipe (51) and a second through hole (42) for introducing an oxygen-containing gas into the gap portion (G) are formed in the cylinder (10).

Description

Hydrogen pressure accumulator

Technical Field

The present disclosure relates to a hydrogen accumulator, and for example, to a hydrogen accumulator in which a cylinder head is screwed into an open end of a cylinder block.

Background

In a high-pressure hydrogen accumulator used in a hydrogen refueling station or the like, for example, a structure in which a cylinder head is screwed into an open end of a cylinder body (cylindrical cylinder body) as disclosed in patent document 1 and non-patent document 1 has been adopted. In this hydrogen accumulator, after hydrogen gas is charged into the cylinder block, the cylinder block is sealed by providing a resin seal (e.g., an O-ring) between the inner peripheral surface of the cylinder block and the outer peripheral surface of the cylinder head. In this way, hydrogen gas hardly reaches the female thread formed at the opening end of the cylinder, and hydrogen-induced cracking from the thread root where stress is concentrated is unlikely to occur.

Further, according to the disclosure of non-patent document 2, when oxygen is contained in a hydrogen gas at a low concentration, the crack propagation rate of hydrogen-induced cracking will be reduced. Further, according to the disclosure of non-patent document 3, oxygen gas is adsorbed on the hydrogen-induced cracked crack surface, thereby preventing hydrogen gas from entering the inside of the material. From these techniques, it is known that oxygen has an effect of preventing hydrogen-induced cracking.

Reference to technical documents

Patent document

Patent document 1: japanese unexamined patent application publication No. 2015-158243

Non-patent literature

Non-patent document 1: standard KHKS 0220 (2010) for extra-high pressure gas plants, 3 months and 31 days 2010, japan high pressure gas safety association, page 26

Non-patent document 2: fukuyama, S. and two others, "fracture toughness and fatigue crack propagation in hydrogen at room temperature and high pressure in AISI4340 Steel", pressure vessel technology, vol.2, 1989, pp.1181-1188

Non-patent document 3: nelson h.g., the "hydrogen environment embrittlement test: major and minor effects "", ASTM Special technology publication, vol.543, 1974, pp.152-169

Disclosure of Invention

Technical problem

The present inventors have found that, in a hydrogen accumulator charged with high-pressure hydrogen gas, hydrogen gas can diffuse through a resin seal despite the small amount of hydrogen gas that diffuses through the resin seal. Therefore, hydrogen gas may reach the female thread formed at the open end of the cylinder, and hydrogen-induced cracking of the cylinder from the root of the thread where stress is concentrated may occur.

Other problems and novel features will become apparent from the following description and the drawings.

Means for solving the problems

In the hydrogen accumulator according to an embodiment, a gap portion that separates an inner peripheral surface of the cylinder block from an outer peripheral surface of the cylinder head is provided between the female screw portion of the cylinder block into which the cylinder head is screwed and the resin seal, and the cylinder block includes a first through hole formed therein that discharges a gas in the gap portion to the discharge pipe and a second through hole that introduces an oxygen-containing gas into the gap portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to this embodiment, it is possible to provide a hydrogen accumulator capable of preventing hydrogen-induced cracking of the cylinder.

Drawings

Fig. 1 is a sectional view of a hydrogen accumulator according to a first embodiment.

Fig. 2 is an enlarged view of region II of fig. 1.

Fig. 3 is a sectional view of a hydrogen accumulator according to a comparative example.

Fig. 4 is a sectional view of a hydrogen accumulator according to a second embodiment.

Fig. 5 is a sectional view of a hydrogen accumulator according to a third embodiment.

Fig. 6 is a sectional view of a hydrogen accumulator according to a fourth embodiment.

Detailed Description

Hereinafter, specific embodiments will be described in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments. Furthermore, the following description and drawings are, where appropriate, condensed for the purpose of clarity.

(first embodiment)

< Structure of Hydrogen gas pressure accumulator >

Hereinafter, the structure of the hydrogen accumulator according to the first embodiment will be described with reference to fig. 1 and 2. Fig. 1 is a sectional view of a hydrogen accumulator according to a first embodiment. Fig. 2 is an enlarged view of region II in fig. 1. As shown in fig. 1, the hydrogen accumulator of the first embodiment includes a cylinder block 10, a cylinder head 20, and a resin seal 30. The hydrogen gas accumulator of the present embodiment is, for example, a high-pressure hydrogen gas accumulator of a hydrogen refueling station. The design pressure of the hydrogen accumulator is, for example, about 80 to 120MPa.

It should be noted that the right-hand XYZ three-dimensional orthogonal coordinate systems shown in the respective drawings coincide with each other, which are shown only for the purpose of convenience in describing positional relationships between components. In general, the XY plane is a horizontal plane, and the positive Z-axis direction is a direction vertically upward. In the example shown in the drawings, the longitudinal direction of the hydrogen accumulator is parallel to the X-axis direction. Therefore, the hydrogen accumulator is generally placed horizontally.

First, the overall structure of the hydrogen accumulator will be explained with reference to fig. 1.

As shown in fig. 1, the cylinder head 20 opens and/or closes the cylinder body 10 filled with hydrogen gas by screwing into the corresponding open end of the cylinder body. The space enclosed by the inner peripheral surface of the cylinder 10 and the inner end surfaces of the two cylinder heads 20 is filled with high-pressure hydrogen. The interior of the cylinder block 10 is sealed by an annular resin seal provided between the inner peripheral surface of the cylinder block 10 and the outer peripheral surface of the cylinder head 20.

The inner peripheral surface of the cylinder 10 and the inner end surface of the cylinder head 20, which are subjected to the high-pressure hydrogen stress, are referred to as compression-resistant portions.

Further, the cylinder head 20 includes a cover body 21 and a nut 22, which will be described in detail below.

Although the example of fig. 1 employs a structure in which both ends of the cylinder 10 are open, a structure in which only one end of the cylinder 10 is open may be employed. The outer peripheral surface of the cylinder block 10 may be reinforced with a carbon fiber reinforced plastic layer (not shown), for example.

The cylinder block 10 and the cylinder head 20 (the cap 21 and the nut 22) are each made of, for example, a steel material such as manganese steel, chromium molybdenum steel, or nickel chromium molybdenum steel. The cylinder body 10, the cover body 21, and the nut 22 may be made of the same kind of steel material or different kinds of steel materials.

The cylinder 10 is, for example, a seamless tube made by forging or extrusion. Regarding the dimensions of the cylinder 10, for example, the internal volume is about 50 to 1000L, the total length is about 1800 to 5000mm, the inner diameter D (see FIG. 2) is about 200 to 400mm, and the thickness t (see FIG. 2) is about 20 to 80mm. To reduce surface scratches that can initiate hydrogen induced cracking, the inner circumferential surface of the cylinder 10 may be mirror polished. For example, surface scratches with a depth of 0.5mm or more and a length of 1.6mm or more are preferably eliminated.

Next, referring to fig. 2, the open end of the cylinder 10 will be described in detail. As shown in fig. 1, since the structures of both open ends of the cylinder 10 are similar to each other, fig. 2 will describe in detail only the structure of the open end of the cylinder 10 on the positive X-axis direction side.

As shown in fig. 2, the inner diameter is enlarged at the opening end of the cylinder 10, and a thread is formed on the inner circumferential surface. That is, the female screw portion 10a is formed in the open end of the cylinder 10. The nut 22 of the cylinder head 20 is screwed into the open end of the cylinder body 10.

The structure of the cylinder head 20 including the cover body 21 and the nut 22 complies with the "screwing structure" requirement specified in the japanese high-pressure gas safety society standard KHKS 0220 (non-patent document 1).

As shown in fig. 2, the cover body 21 is a cylindrical member having a stepped portion whose central axis C coincides with the central axis of the cylinder block 10. The cover body 21 includes a flange portion 21a. In the lid body 21, a portion having a larger diameter and located in the negative X-axis direction with respect to the flange portion 21a is referred to as a large diameter portion, and a portion having a smaller diameter and located in the positive X-axis direction with respect to the flange portion 21a is referred to as a small diameter portion.

The diameter of the flange portion 21a is larger than the inner diameter of the main body portion (portion other than the open end) of the cylinder 10, but smaller than the inner diameter of the open end of the cylinder 10. Therefore, the cap 21 can be inserted into the cylinder 10 from the open end of the cylinder 10. The flange portion 21a contacts the stepped portion 10b between the main body portion and the enlarged open end of the cylinder block 10.

As shown in fig. 2, the diameter of the large diameter portion of the cap body 21 is substantially equal to the inner diameter of the main body portion of the cylinder body 10, and the cap body 21 is fitted into the main body portion of the cylinder body 10. On the other hand, the shaft diameter of the small diameter portion of the cap body 21 is substantially equal to the inner diameter of the nut 22, and is fitted into the through hole of the nut 22. The small diameter portion of the cover body 21 is rotatable relative to the nut 22. Further, in the example of fig. 2, the length of the small diameter portion of the cover 21 is substantially equal to the height (length in the X-axis direction) of the nut 22.

The nut 22 is an externally threaded nut whose central axis C coincides with the central axis of the cylinder 10. That is, the outer peripheral surface of the nut 22 is a threaded surface. The cap 20 is fixed to the cylinder block 10 by inserting the small diameter portion of the cap 21 into the through hole of the nut 22 while the nut 22 is screwed into the open end of the cylinder block 10. Specifically, when the nut 22 is screwed into the opening end of the cylinder 10, the nut 22 moves in the negative X-axis direction. When the nut 22 pushes the flange portion 21a against the stepped portion 10b of the cylinder 10, the nut 22 cannot move forward any more, so that the cap body 21 and the nut 22 are fixed to the cylinder 10. It can be seen that the flange portion 21a serves as a stop mechanism during the process of screwing the nut 22 into the open end of the cylinder 10.

The resin seal 30 (e.g., an O-ring) is an annular resin member having a central axis C coinciding with the central axis of the cylinder 10. As shown in fig. 2, the resin seal 30 is provided between the inner peripheral surface of the cylinder block 10 and the outer peripheral surface of the cylinder head 20. More specifically, as shown in fig. 2, the resin seal 30 is fitted into an annular groove 21b formed on the outer peripheral surface of the large-diameter portion of the lid body 21. That is, the interior of the cylinder 10 is sealed by the resin seal 30 provided between the inner peripheral surface of the main body portion of the cylinder 10 and the outer peripheral surface of the large diameter portion of the lid 21.

As shown in fig. 2, a gap G is provided between the resin seal 30 and the female screw portion 10a of the cylinder block 10 to separate the inner peripheral surface of the cylinder block 10 from the outer peripheral surface of the cylinder head 20. Specifically, the outer peripheral surface of the flange portion 21a of the lid body 21 is provided with an annular circular gap portion G.

In the hydrogen accumulator of the present embodiment, in addition to the through-hole (first through-hole) 41 that discharges the gas in the gap portion G into the discharge pipe 51, a through-hole (second through-hole) 42 that introduces the oxygen-containing gas into the gap portion G is formed in the cylinder 10. Such as, but not limited to, air. The discharge pipe 51 is a pipe for safely discharging the hydrogen gas leaked from inside the cylinder 10 to the gap portion G into the atmosphere. When an emergency such as a defect in the resin seal 30 occurs, hydrogen gas can be released through the bleed-off pipe 51.

As described above, the present inventors have found that, in a hydrogen accumulator charged with high-pressure hydrogen gas, hydrogen gas can diffuse through the resin seal 30 despite the small amount of hydrogen gas that diffuses through the resin seal. In this case, hydrogen gas may reach the female thread portion 10a of the cylinder block 10 through the gap portion G, possibly causing hydrogen-induced cracking of the cylinder block from the thread root where stress is concentrated.

In order to solve the above problem, in the hydrogen accumulator of the present embodiment, the through hole 42 is formed in the cylinder 10 in addition to the through hole 41 connected to the discharge pipe 51. Since the through-holes 41 are connected to the discharge pipe 51, the oxygen-containing gas (i.e., air) can be sucked from the through-holes 42 into the gap portion G, for example, by natural convection. Since the gap portion G communicates with the female thread portion 10a of the cylinder block 10, oxygen gas that can effectively prevent hydrogen induced cracking can reach the thread root of the female thread portion 10a. In this way, hydrogen induced cracking of the cylinder 10 from the root of the thread can be prevented.

The formation positions of the through

holes

41 and 42 are not particularly limited as long as they are between the resin seal 30 and the female screw portion 10a of the cylinder block 10. The closer the through

holes

41 and 42 are located to the pressure-resistant portions, i.e., the closer they are located to the resin seal 30, the more they are subjected to stress from the high-pressure hydrogen gas charged in the cylinder 10. Specifically, the greater the stress received by the corner portions of the through

holes

41 and 42 on the inner peripheral surface of the cylinder 10. Therefore, the formation positions of the through

holes

41 and 42 are preferably spaced from the resin seal 30 in the X-axis positive direction in fig. 2.

Specifically, as shown in FIG. 2, the stress applied by the high-pressure hydrogen gas is assumed to act at a distance of about 2.5 × (r × t) in the positive direction of the X-axis from the pressure-resistant portion ^1/2 mm, where r is the average radius (mm) of the cylinder 10 and t is the thickness (mm) of the cylinder 10. The average radius r of the cylinder 10 is an average of the inner radius and the outer radius of the cylinder 10. Thus, the average radius r (mm) can be expressed as r = (D + t)/2, where D is the inner diameter (mm) and t is the thickness (mm).

On the other hand, when the distance of the through

holes

41 and 42 from the female thread portion 10a is too close, stress of the female thread portion 10a may be increased.

Therefore, as shown in fig. 2, the through

holes

41 and 42 are formed, for example, in the central portion in the longitudinal direction (X-axis direction) of the cylinder block 10 opposed to the gap portion G.

The through hole 41 connected to the drain pipe 51 is provided, for example, but not particularly limited to, vertically downward. With this structure, the moisture accumulated in the void portion G due to condensation or the like can be discharged together with the gas. On the other hand, the through hole 42 for introducing oxygen is opposed to the through hole 41 through the cylinder head 20, for example, but not particularly limited. With this structure, oxygen introduced from the through-holes 42 will flow to the through-holes 41, thereby making it easy for oxygen to be distributed throughout the void portion G.

The larger the diameter of the through

holes

41 and 42, the higher the stress applied to the stress concentration portion, and the more easily the cracking due to metal fatigue is induced. On the other hand, when the diameters of the through

holes

41 and 42 are too small, the release of hydrogen and the introduction of oxygen will be difficult to occur, and it will be difficult to round the corner portions of the through

holes

41 and 42 on the inner peripheral surface of the cylinder 10. Therefore, the diameters of the through

holes

41 and 42 are each set to be approximately equal to 2 to 5% of the average radius r (mm) of the cylinder 10, for example. For example, the through

holes

41 and 42 each have a diameter of about 2 to 12mm.

Further, since sharp corner portions are liable to crack due to metal fatigue, the corner portions of the through

holes

41 and 42 on the inner peripheral surface of the cylinder block 10 may be, for example, subjected to a round-corner working.

The number of the through

holes

41 and 42 may be plural.

< Structure of Hydrogen gas pressure accumulator of comparative example >

Hereinafter, the structure of the hydrogen accumulator according to the comparative example is described with reference to fig. 3. FIG. 3 is a sectional view of a hydrogen accumulator of a comparative example. Fig. 3 corresponds to fig. 2.

As shown in fig. 3, in the hydrogen accumulator of the comparative example, the through-hole 41 that discharges the gas in the gap portion G to the discharge pipe 51 was formed only in the cylinder 10, and the through-hole 42 that introduces the oxygen-containing gas into the gap portion G shown in fig. 2 was not formed.

Thus, oxygen gas which can effectively prevent hydrogen induced cracking cannot be introduced into the gap portion G, so that the cylinder block 10 is liable to hydrogen induced cracking from the thread root where stress is concentrated. Specifically, the closer the distance between the thread root and the gap G is, the more likely the crack is generated.

It should be noted that the hydrogen-induced cracking of the hydrogen accumulator described above is fatigue failure due to repeated charging and discharging of high-pressure hydrogen gas.

As described above, in the hydrogen accumulator of the present embodiment, since the through-hole 42 that introduces the oxygen-containing gas into the gap portion G is formed in the cylinder block 10, the oxygen gas that can effectively prevent hydrogen-induced cracking can be introduced into the gap portion G through the through-hole 42. Since oxygen introduced into the gap portion G can reach the thread root of the female thread portion 10a, hydrogen-induced cracking of the cylinder block 10 from the thread root can be reduced.

(second embodiment)

Hereinafter, with reference to fig. 4, the structure of the hydrogen accumulator of the second embodiment is described. Fig. 4 is a sectional view of a hydrogen accumulator of a second embodiment. Fig. 4 corresponds to fig. 2 of the first embodiment.

As shown in fig. 4, in the hydrogen accumulator of the second embodiment, the through-hole 42 for introducing the oxygen-containing gas into the gap portion G is connected to the check valve CV via the introduction pipe 2, and the rest of the structure is similar to that of the hydrogen accumulator of the first embodiment shown in fig. 2.

In the hydrogen accumulator of the second embodiment, as in the hydrogen accumulator of the first embodiment, oxygen gas that effectively prevents hydrogen induced cracking can be introduced into the gap portion G through the through-hole 42, thereby reducing hydrogen induced cracking of the cylinder block 10 from the root of the thread.

Further, in the hydrogen accumulator of the second embodiment, since the through hole 42 is connected to the check valve CV, the gas in the void portion G is not discharged from the through hole 42. In this manner, when an emergency such as a defect in the resin seal 30 occurs, hydrogen gas is safely released from the discharge pipe 51 to the atmosphere through the through hole 41 without being released through the through hole 42.

On the other hand, in the hydrogen accumulator of the first embodiment, in the above case, although hydrogen gas can be released through the through-hole 42. However, even when hydrogen gas is released through the through-hole 42 of the hydrogen accumulator of the first embodiment, the amount of hydrogen gas released is extremely small, and therefore there is no particular safety concern.

(third embodiment)

Hereinafter, with reference to fig. 5, the structure of the hydrogen accumulator of the third embodiment is described. Fig. 5 is a sectional view of a hydrogen accumulator of a third embodiment. Fig. 5 corresponds to fig. 2 of the first embodiment.

As shown in fig. 5, in the hydrogen accumulator of the third embodiment, the through-hole 42 for introducing the oxygen-containing gas into the gap portion G is connected to the pump P via the introducing pipe 52, and the rest of the structure is similar to that of the hydrogen accumulator of the first embodiment shown in fig. 2.

As in the hydrogen accumulator of the second embodiment, a check valve CV may be provided in the introduction pipe 2 provided between the through hole 42 and the pump P.

Since the hydrogen accumulator of the third embodiment includes the pump P, it is possible to forcibly introduce oxygen gas, which can effectively prevent hydrogen-induced cracking, into the void portion G through the through hole 42. In this way, hydrogen-induced cracking of the cylinder 10 from the root of the thread can be reduced more effectively than in the hydrogen accumulator of the first embodiment.

(fourth embodiment)

Hereinafter, with reference to fig. 6, the structure of the hydrogen accumulator of the fourth embodiment is described. Fig. 6 is a sectional view of a hydrogen accumulator of a fourth embodiment. Fig. 6 corresponds to fig. 2 of the first embodiment.

As shown in fig. 6, in the hydrogen accumulator of the fourth embodiment, a relief valve RV is provided in a relief pipe 51. The relief valve RV is closed when the pressure in the gap portion G is atmospheric pressure, and is opened when the pressure in the gap portion G rises from atmospheric pressure to a preset pressure. The remaining structure is similar to that of the hydrogen accumulator of the third embodiment shown in fig. 5.

The hydrogen accumulator of the fourth embodiment includes a pump P, as with the hydrogen accumulator of the third embodiment. Therefore, it can forcibly introduce oxygen gas, which can effectively prevent hydrogen-induced cracking, into the void portion G through the through-hole 42.

The hydrogen accumulator of the fourth embodiment further includes a relief valve RV provided in the relief pipe 51. By increasing the pressure in the gap G in this manner, the partial pressure of oxygen in the gap G can be increased and the diffusion of hydrogen gas in the resin seal 30 can be prevented, so that hydrogen-induced cracking of the cylinder 10 from the root of the thread can be more effectively prevented than in the hydrogen accumulator of the third embodiment.

While the present disclosure disclosed by the present inventors has been specifically described above according to the embodiments, it goes without saying that the present disclosure is not limited to these embodiments, but may be changed in various ways without departing from the spirit of the present disclosure.

This application is based on and claims priority from japanese patent application No. 2018-187193, having a filing date of 2018, 10/2, the entire disclosure of which is incorporated herein.

List of reference numerals

10. Cylinder body

10a female threaded portion

10b step part

20. Cylinder cover

21. Cover body

21a flange portion

21b annular groove

22. Nut

30. Resin sealing member

41 42 through hole

51. Drain pipe

52. Lead-in tube

CV check valve

G void part

P pump

RV relief valve

Claims

1. A hydrogen accumulator, comprising:

a cylinder filled with hydrogen gas;

a cylinder head screwed into a female screw portion formed in an open end of the cylinder block; and

an annular resin seal provided between an inner peripheral surface of the cylinder block and an outer peripheral surface of the cylinder head, wherein,

a gap portion for separating the inner peripheral surface of the cylinder block from the outer peripheral surface of the cylinder head is provided between the female screw portion of the cylinder block and the resin seal, and

a first through hole for discharging the gas in the space portion to a discharge pipe and a second through hole for introducing an oxygen-containing gas into the space portion are formed in the cylinder;

the first through-hole and the second through-hole are provided between the female thread portion and the resin seal.

2. The hydrogen accumulator of claim 1 further comprising a check valve connected to the second through-hole.

3. A hydrogen accumulator as claimed in claim 1 or 2, further comprising a pump connected to the second through-hole.

4. The hydrogen accumulator of claim 3 further comprising a bleed valve disposed within the bleed tube.

5. A hydrogen accumulator as claimed in claim 1 or 2, wherein the second through hole is provided at a central portion opposite to the void portion in a length direction of the cylinder block.

6. A hydrogen accumulator as claimed in claim 1 or 2, wherein corner portions of said second through holes on said inner peripheral surface of said cylinder block are subjected to a round-corner process.